Glaucoma is a leading cause of irreversible blindness in the United States. This disease affects 2% of the population. Treatment of glaucoma is directed at lowering the intraocular pressure first, through medical therapy, followed by surgery. In this grant application, a non-invasive laser treatment for glaucoma will be investigated which has the capability of replacing conventional glaucoma filtration surgery. The laser filtration procedure may also have a major impact on the physician's approach to the management of glaucoma. A Candela flashlamp excited dye laser emitting in the visible region will be used to create a fistula through the sclera (sclerostomy) to lower intraocular pressure by allowing controlled egress of aqueous humor. The technique involves locally dying the sclera with Methylene Blue (1%) and ablating the sclera via an ab-interno (from within) approached. In Phase I, we developed a slit-lamp delivery system which, coupled to a flashlamp excited dye laser, will accomplish ab-interno energy delivery to the eye. We also determined the feasibility of creating sclerotomies in-vitro and in-vivo in rabbits and monkeys using pulse duration in the microsecond range. In Phase II of this study, we will examine the clinical significance of ablation effectiveness as a function of pulse duration, energy and spot diameter and optimize these parameters. We will then conduct a clinical study to determine the safety and effectiveness of this procedure in humans.